1. Field of the Invention
The present invention relates to a method of processing an input audio signal, an audio reproduction system, and an audio processing apparatus.
2. Description of the Related Art
Audio signal processing techniques using both analog and digital electronics are commonplace. For instance, techniques for processing audio signals exist to enhance the perceived bass response of a loudspeaker, an example of which is described in United Kingdom patent number 2 469 573 B, assigned to the present applicant. Furthermore, techniques exist for reducing harmonic distortion of audio by a loudspeaker, an example of which is described in United Kingdom patent publication number 2 491 130 A, the corresponding application of which is also assigned to the present applicant.
Whilst numerous techniques exist for improving the frequency and phase responses of audio reproduction systems, the very properties of the construction of the audio reproduction systems can cause much greater distortions that are many times more noticeable to a listener than frequency and phase distortions. Many electronic devices suitable for reproducing audio signals are not designed with high fidelity reproduction in mind—the addition of audio reproduction functionality having either being born out of necessity or simply being an afterthought.
Thus, the lack of suitable construction techniques for many consumer-level electronic devices can often lead to distortion of audio during playback. This is in particular due to mechanical vibration of the components of the device itself, usually caused by audio including a resonant frequency of the device being supplied to a loudspeaker located within the device. Many manufacturers attempt to solve this issue by introducing dampening materials into the device, such as rubber gaskets around interfaces between surfaces. However, this is unsatisfactory in many situations, as adding these dampening materials can in many cases be economically unviable. A technical approach to providing an innovative solution to this problem, operating within economic constraints, has hitherto been unforthcoming.